: I've only heard of this 'Age of Discovery' on the Halo wikipedia page. I'd
: honestly like to know where they got that reference so that I might go and
: make my own judgment on that one.

Actually, I found its exact name on the HBO Mural Page. In a removed cutscene features on the Halo 2 behind the scenes disk, when the Elites are bumped down on the ladder, Truth shows the Arbiter the Hall of Murals, which tell the story of the Covenant's past.